Why Are Whales Dying? Because of Us

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Despite efforts including policies implemented by the U.S. and Canadian governments, right whales, one of the most endangered species in the ocean, are still dying because of us humans. In a new study in Conservation Biology, Julie van der Hoop and Michael Moore of the Massachusetts’ Woods Hole Oceanographic Institution analyzed data about the deaths of eight species of large whales in the northwest Atlantic between 1970 and 2009 during which they recorded 1,762 deaths and serious (likely fatal) injuries occurred among eight species of whales.

122 right whales (Eubalaena glacialis), 473 humpbacks (Megaptera novaeangliae), 257 fin whales (Balaenoptera physalus) and, as the journal Nature says, “scores” of whales of other species died. The researchers were only able to assign a reason for the whales’ deaths in 47 percent of the cases. In 67 percent of these, the cause of death was human activity.

Specifically, entanglement of whales in fishing nets was the main reason for their deaths, followed by natural deaths and vessel strikes. Researchers found that the likelihood of whales being entangled or struck by vessels with fatal results “increased significantly from 1990 through 2009.” The year after numerous efforts to prevent such had been enacted saw “no significant change in the local intensity of all or vessel-strike mortalities.”

These findings are especially disappointing as both the U.S. and Canadian governments have created regulatory efforts to lessen fatalities caused by human activity, including the 2008 U.S. “ship strike rule” that limits the speed of ships in certain areas.

Moore did emphasize that the findings do have to be analyzed with care as they present what is a “broad brush analysis” and the researchers were not able to determine the cause of death for all 53 percent of cases. He also notes local efforts that have “undoubtedly” had benefits but are not apparent in a more wide-scale review. One such local effort was to move shipping lanes in the Bay of Fundy between the Canadian provinces of New Brunswick and Nova Scotia to help protect right whales.

The findings are also useful in that they suggest where efforts can be focused to prevent whale deaths. The researchers found a spike in whale deaths in the waters around Cape Hatteras, just north of Morehead City in North Carolina, a region where hardly any measures have been taken to prevent whale deaths. The study makes clear that such should at least be considered.

The U.S. “ship strike rule” is set to expire next year. Greg Silber, a marine-mammal researcher at the US National Marine Fisheries Service, tells Nature that, after the rule was implemented, compliance was “poor” but that it has since improved. Van der Hoop’s and Moore’s study suggested that speed restrictions on ships be continued and Silber noted that these could also be required for smaller ships.

Lest it seem that we can do little to monitor and prevent human activity with lethal results for whales, Moore said that he has been having a “hard time” spending funding from the U.S. government to perform autopsies on right whales, which he dubbed “really positive sign.” The study’s findings suggest that we need to maintain efforts to protect whales in U.S. and Canadian waters and, if anything, to be more aggressive in preventing whale deaths caused unnecessarily by us.